ios - 在 Swift Xcode 中以编程方式下拉列表菜单

Question

我做了一个下拉 gender ，它工作正常但是我在同一个 viewcontroller 上有另一个下拉，它显示下拉但是当我选择项目时它给出错误fatal error: expectedly found nil while unwrapping an Optional value 我试过了，但很困惑。帮我解决 bloodList 下拉菜单。

import UIKit

class ViewController: UIViewController {

@IBOutlet weak var genderButton: UIButton!
@IBAction func genderButton(_ sender: Any) {
    self.PressDrop()
    view.addSubview(genderTable)
}
@IBOutlet weak var genderTable: UITableView!

var flag = 1
var dropDownList = [String]()
@IBOutlet weak var bloodButton: UIButton!
var bloodList = [String]()
@IBAction func bloodButton(_ sender: Any) {
    self.PressBlood()
    view.addSubview(bloodTable)
}
@IBOutlet weak var bloodTable: UITableView!

    override func viewDidLoad() {
    super.viewDidLoad()

    dropDownList = ["Male", "Female", "Other"]
    genderTable.delegate = self
    genderTable.dataSource = self
    genderTable.isHidden = true
    view.addSubview(genderTable) 
    genderTable.layer.cornerRadius = 10

    bloodList = ["A+", "A-", "AB+", "AB-"] 
    bloodTable.delegate = self
    bloodTable.dataSource = self
    bloodTable.isHidden = true
    view.addSubview(bloodTable)
    bloodTable.layer.cornerRadius = 10  
}

func PressDrop() {
    if flag == 0 {
        UIView.setAnimationDuration(0.5)
        self.genderTable.isHidden = true
        self.flag = 1
    }
    else{
        UIView.setAnimationDuration(0.5)
        self.genderTable.isHidden = false
        self.flag = 0
    }
}

func PressBlood() {
    if flag == 0 {
        UIView.setAnimationDuration(0.5)
        self.bloodTable.isHidden = true
        self.flag = 1
    }
    else{
        UIView.setAnimationDuration(0.5)
        self.bloodTable.isHidden = false
        self.flag = 0
    }
}

func numberOfSections(in tableView: UITableView) -> Int {
    return 1
}

func tableView(_ tableView: UITableView, numberOfRowsInSection section: Int) -> Int {
    return dropDownList.count

}

func tableViewBlood(_ tableView: UITableView, numberOfRowsInSection section: Int) -> Int {
    return bloodList.count
}

func tableView(_ tableView: UITableView, heightForRowAt indexPath: IndexPath) -> CGFloat {
    return 50
}

func tableView(_ tableView: UITableView, cellForRowAt indexPath: IndexPath) -> UITableViewCell {
    let cell = genderTable.dequeueReusableCell(withIdentifier: "cell", for: indexPath)
    cell.textLabel!.text = dropDownList[indexPath.row]
    return cell
}

func tableViewTwo(_ tableView: UITableView, cellForRowAt indexPath: IndexPath) -> UITableViewCell {
    let cell = bloodTable.dequeueReusableCell(withIdentifier: "bloodCell", for: indexPath)
    cell.textLabel!.text = bloodList[indexPath.row]
    return cell
}

 func tableView(_ tableView: UITableView, didSelectRowAt indexPath: IndexPath) {

    let   selectedData = dropDownList[indexPath.row]
    genderButton.setTitle(selectedData, for: .normal)
    self.genderTable.isHidden = true
    self.flag = 
    let indexPath = genderTable.indexPathForSelectedRow
    let currentCell = genderTable.cellForRow(at: indexPath!)! as UITableViewCell
    let finalresult = currentCell.textLabel!.text!
    print("\(finalresult)")
}

private func tableViewTwo(_ tableView: UITableView, didSelectRowAt indexPath: IndexPath) {
    let   selectedBlood = bloodList[indexPath.row]
    bloodButton.setTitle(selectedBlood, for: .normal)
    self.bloodTable.isHidden = true
    self.flag = 1
    let indexPathTwo = bloodTable.indexPathForSelectedRow
    let currentCellBlood = bloodTable.cellForRow(at: indexPathTwo!)! as UITableViewCell
    let finalresultBlood = currentCellBlood.textLabel!.text!
    print("\(finalresultBlood)")
}
}

Answer 1

您不能更改 tableView 的默认委托(delegate)方法，请在委托(delegate)方法中提供条件，如下所示:

func tableView(_ tableView: UITableView, numberOfRowsInSection section: Int) -> Int {
      if tableView == genderTable {
          return dropDownList.count
      }
      return bloodList.count
    }

对其余的委托(delegate)方法也进行类似的更改。

func tableView(_ tableView: UITableView, cellForRowAt indexPath: IndexPath) -> UITableViewCell {
    if tableView == genderTable {
        let cell = genderTable.dequeueReusableCell(withIdentifier: "cell", for: indexPath)
        cell.textLabel!.text = dropDownList[indexPath.row]
        return cell
} else {
        let cell = bloodTable.dequeueReusableCell(withIdentifier: "bloodCell", for: indexPath)
        cell.textLabel!.text = bloodList[indexPath.row]
        return cell
}

func tableView(_ tableView: UITableView, didSelectRowAt indexPath: IndexPath) {
      if tableView == genderTable { 
        let   selectedData = dropDownList[indexPath.row]
        genderButton.setTitle(selectedData, for: .normal)
        self.genderTable.isHidden = true 
        let currentCell = genderTable.cellForRow(at: indexPath)! as UITableViewCell
        let finalresult = currentCell.textLabel!.text!
        print("\(finalresult)")
     } else {
        let   selectedBlood = bloodList[indexPath.row]
        bloodButton.setTitle(selectedBlood, for: .normal)
        self.bloodTable.isHidden = true
        let currentCellBlood = bloodTable.cellForRow(at: indexPath)! as UITableViewCell
        let finalresultBlood = currentCellBlood.textLabel!.text!
        print("\(finalresultBlood)")
   }
}